Project description:Protein kinases are key signaling nodes that regulate fundamental biological and disease processes. Illuminating kinase signaling from multiple angles can provide deeper insights into disease mechanisms and improve therapeutic targeting. While fluorescent biosensors are powerful tools for visualizing live-cell kinase activity dynamics in real time, new molecular tools are needed that enable recording of transient signaling activities for post hoc analysis and targeted manipulation. Here, we develop a light-gated kinase activity coupled transcriptional integrator (KINACT) that converts dynamic kinase signals into “permanent” fluorescent marks. KINACT enables robust monitoring of kinase activity across scales, accurately recording subcellular PKA activity, highlighting PKA activity distribution in 3D cultures, and identifying PKA activators and inhibitors in high-throughput screens. We further leverage the ability of KINACT to drive signaling effector expression to allow feedback manipulation of the balance of GαsR201C-induced PKA and ERK activation and dissect the mechanisms of oncogenic G protein signaling.
Project description:RNAseq of livers from High Fat Diet and Low Fat Diet fed mice, sampled every 4 hours over one full cycle, living in either short light, long light, or equal light photoperiods
Project description:Gene expression is tightly regulated in space and time. To dissect this process with high temporal resolution, we introduce an optogenetic tool termed BLInCR (Blue Light-Induced Chromatin Recruitment) that combines rapid and reversible light-dependent recruitment of effector proteins with a real-time readout for transcription. We used BLInCR to control the activity of a reporter gene cluster in the human osteosarcoma cell line U2OS by reversibly recruiting the viral transactivator VP16. RNA production was detectable ~2 minutes after VP16 recruitment and readily decreased when VP16 dissociated from the cluster in the absence of light. Quantitative assessment of the activation process revealed biphasic activation kinetics with a pronounced early phase in cells treated with the histone deacetylase inhibitor SAHA. Comparison with kinetic models for transcription activation suggests that the gene cluster undergoes a maturation process when activated. We anticipate that BLInCR will facilitate the study of transcription dynamics in living cells.
Project description:Complexes containing INTS3 and either NABP1 or NABP2 were initially characterized in DNA damage responses, but their biochemical function remained unknown. Using affinity purifications and HIV Integration Targeting-Sequencing (HIT-Seq), we find that these complexes are part of the Integrator complex, which binds RNA Polymerase II and regulates specific target genes. Integrator cleaves snRNAs as part of their processing to their mature form in a mechanism that is intimately coupled with transcription termination. However, HIT-Seq reveals that Integrator also binds to the 3’ end of replication-dependent histones and promoter proximal regions of genes with polyadenylated transcripts. Depletion of Integrator subunits results in transcription termination failure, disrupting histone mRNA processing, and leading to polyadenylation of snRNAs and histone mRNAs. Furthermore, promoter proximal binding of Integrator negatively regulates expression of genes whose transcripts are normally polyadenylated. Integrator recruitment to all three gene classes is DSIF-dependent, suggesting that Integrator functions as a termination complex at DSIF-dependent RNA Polymerase II pause sites. HITseq was used to interrogate chromatin binding sites of of proteins in the complex (including INIP, INTS3, INTS9, INTS11, NABP1, NABP2, NELFA, NELFB, NELFCD, NELFE, SPT5). These proteins were fused to LEDGF-IBD and expressed in mouse LEDGF-/-MEF cells. The fusion proteins then target HIV integration to the chromatin binding sites. The HIV integration sites were identified using linker-mediated PCR and highthroughput sequencing and serve as surrogate for chromatin binding sites. Mapping was done using mouse genome mm9.
Project description:A 14k cDNA microarray was used to examine gene expression difference in hypothalamus of chickens exposed to a chronic unpredictable light (UL) rhythm, in relation to chickens living under predictable light (PL). Offspring of UL and PL parents were thereafter compared in the same manner, with the only exception that both offspring groups lived under the PL treatment, hence investigating the effect of having a parent living under unpredictable light.
Project description:Lee SY, Chea JS, Zhao BX, Xu C, Udeshi ND, Roh H, Kim C, Cho K, Carr SA, Ting A. 2022
The incorporation of light-responsive domains into engineered proteins has produced optogenetic tools with the ability to regulate protein localization, interactions, and function with light. We introduced this mode of regulation into proximity labeling (PL), which has been a cornerstone technique for high-resolution proteomic mapping of organelles and interactomes in living cells. Through a combination of structure-guided screening and yeast display directed evolution, we inserted the light sensitive LOV domain into a surface exposed loop of the PL enzyme TurboID to rapidly and reversibly control its labeling activity with low-power blue light. We showed that "LOV-Turbo" works in multiple organelles and cell types and can dramatically reduce background labeling in biotin-rich environments such as living neurons. We utilized LOV-Turbo's reversibility to perform pulse-chase labeling followed by organelle fractionation to discover endogenous proteins that traffick between endoplasmic reticulum, nuclear, and mitochondrial compartments under cellular stress. Lastly, we showed that instead of external light, LOV-Turbo can be activated by bioluminescence resonance energy transfer from proximal luciferase in living cells, opening the door to chemical and/or interaction dependent PL. Overall, LOV-Turbo increases the spatial and temporal precision of PL and expands the scope of experimental questions that can be addressed using PL.
Project description:MicroRNA (miRNA) homeostasis is crucial for the post-transcriptional regulation of their target genes and miRNA dysregulation has been linked to multiple diseases, including cancer. The mechanistic steps of miRNA biogenesis are well understood at molecular level1,2. Subsequent miRNA duplex loading into members of the Argonaute (Ago) protein family, representing the core of the RNA-induced silencing complex (RISC), is pivotal to miRNA-mediated gene silencing3-5. The Integrator complex has been previously identified as important regulator of RNA maturation, RNA polymerase II pause-release, and premature transcriptional termination, processes dependent on Integrator’s catalytical activity6-9. Here we report that absence of the Integrator complex leads to a global loss of mature miRNAs. By incorporating 4-Thiouridine (s4U) in nascent transcripts, we traced miRNA fate from biogenesis to stabilization and identified Integrator to be essential for proper miRNA assembly into RISC. Indeed, Integrator enhances miRNA-Ago2 interaction in vitro, which functionally translates to amplified miRNA target cleavage. These findings demonstrate for the first time cytoplasmic Integrator complex functions and stress an indirect role of Integrator in transcription regulation through modulation of miRNA abundance and stability.
Project description:Cellular homeostasis requires transcriptional outputs to be coordinated, and many events post transcription initiation can dictate the levels and functions of mature transcripts. To systematically identify regulators of inducible gene expression, we performed high-throughput RNAi screening of the Drosophila Metallothionein A (MtnA) promoter. This revealed that the Integrator complex, which has a well-established role in 3' end processing of small nuclear RNAs (snRNAs), attenuates MtnA transcription during copper stress. Integrator complex subunit 11 (IntS11) endonucleolytically cleaves MtnA transcripts, resulting in premature transcription termination and degradation of the nascent RNAs by the RNA exosome, a complex also identified in the screen. Using RNA-seq, we then identified >400 additional Drosophila protein-coding genes whose expression increases upon Integrator depletion. We focused on a subset of these genes and confirmed that Integrator is bound to their 5' ends and negatively regulates their transcription via IntS11 endonuclease activity. Many non-catalytic Integrator subunits, which are largely dispensable for snRNA processing, also have regulatory roles at these protein-coding genes, possibly by controlling Integrator recruitment or RNA polymerase II dynamics. Altogether, our results suggest that attenuation via Integrator cleavage limits production of many full-length mRNAs, allowing precise control of transcription outputs.
Project description:Efficient release of promoter-proximally paused Pol II into productive elongation is essential for gene expression. Recently, we reported that the Integrator complex can bind paused Pol II and drive premature transcription termination, potently attenuating the activity of target genes. Premature termination requires RNA cleavage by the endonuclease subunit of Integrator, but the roles of other Integrator subunits in gene regulation have yet to be elucidated. Here, we report that Integrator subunit 8 (IntS8) is critical for transcription repression through its association with Protein Phosphatase 2A (PP2A). We find that Integrator-bound PP2A dephosphorylates the Pol II C-terminal domain and Spt5, and prevents the transition to productive elongation. Blocking PP2A association with Integrator thus stimulates pause release and gene activation. These results reveal a second catalytic function associated with Integrator-mediated transcription termination, and suggest a new model for the control of productive elongation involving active competition between transcriptional kinases and phosphatases.
Project description:Complexes containing INTS3 and either NABP1 or NABP2 were initially characterized in DNA damage responses, but their biochemical function remained unknown. Using affinity purifications and HIV Integration Targeting-Sequencing (HIT-Seq), we find that these complexes are part of the Integrator complex, which binds RNA Polymerase II and regulates specific target genes. Integrator cleaves snRNAs as part of their processing to their mature form in a mechanism that is intimately coupled with transcription termination. However, HIT-Seq reveals that Integrator also binds to the 3’ end of replication-dependent histones and promoter proximal regions of genes with polyadenylated transcripts. Depletion of Integrator subunits results in transcription termination failure, disrupting histone mRNA processing, and leading to polyadenylation of snRNAs and histone mRNAs. Furthermore, promoter proximal binding of Integrator negatively regulates expression of genes whose transcripts are normally polyadenylated. Integrator recruitment to all three gene classes is DSIF-dependent, suggesting that Integrator functions as a termination complex at DSIF-dependent RNA Polymerase II pause sites.